A Long Piece of Ribbon Wired Along Both Long Edges

question 48

Multiple Choice

A long piece of ribbon wired along both long edges is twisted into a helix and wrapped around individual pipe cleaners that have been rolled into spools;this grouping is then twisted (super coiled) again to condense it.This could be best used as a simple model for

• A)a plasma membrane,where the pipe cleaners represent the phospholipid bilayer and the ribbon represents proteins embedded in the membrane.
• B)a cell wall.
• C)a mitochondrion.
• D)a chromosome,where the pipe cleaners represent bundles of proteins around which the DNA double helix (wired ribbon)is wrapped.

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Definitions:

Asymmetric Carbon

A carbon atom bonded to four different groups, creating a chiral center.

Dextro-

Prefix indicating the right-handed (clockwise) configuration of a chiral molecule, often used in stereochemistry.

Levorotatory

Relating to a substance that rotates the plane of polarized light to the left.

Optical Activity

The ability of a molecule to rotate plane-polarized light, a property used to distinguish between enantiomers in stereochemistry.